JPH0743226B2 - Condenser cooling water flow controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a condenser cooling water flow rate control device, and in particular to a condenser in which the cleanliness of the condenser cooling pipe changes depending on operating conditions, cleaning, etc. The present invention relates to a condenser cooling water flow rate control device for a power plant so that the degree of vacuum changes.

[Conventional technology]

FIG. 1 is a schematic diagram showing a condenser cooling water system by taking a thermal power plant as an example. In the figure, 1 is a generator output detector, 2 is a cooling water inlet temperature detector, 3 is a cooling water outlet temperature detector, 4 is a cooling water flow rate detector, and corresponds to each detector shown in FIG. To do.

In recent years, due to the increase of nuclear power plants and the expansion of daily load change range, not only new thermal power plants but also existing large-capacity thermal power plants have been modified in various ways and intermediate load operation has become common. For cooling water pumps, in order to reduce the power of the pump shaft during partial load, there are many cases in which a movable vane pump is adopted so that the pump water supply amount can be adjusted to the cooling water amount that matches the condenser heat load. .

Conventionally, the amount of condenser cooling water has been controlled by controlling the blade opening of the movable blade cooling water pump as shown in FIG. 3 by using a control device as shown in FIG.

In FIG. 2, 1 is a generator output detector, 2 is a cooling water inlet temperature detector, 3 is a cooling water outlet temperature detector, 4 is a cooling water flow rate detector, and 5, 6 and 7 are flow rate commands respectively. A value generator, an adder, and a regulator. 5 is a flow rate command value generator that is a program of Fig. 3 as it is. Economic operation given as a function of condenser cooling water inlet / outlet temperature difference (ΔT) limit line and generator output with cooling water inlet temperature as a parameter. The high value output with the line is used as the flow rate command value.

Here, the ΔT control line is obtained from the environmental regulation value (generally around 7 ° C) by the formula (1), and the economic operation line is created by the dotted line in Fig. 4 for each generator output. Here Q: condenser heat load (Kcal / h) G _W: cooling water ^{(m 3 / h) C P} : specific heat at constant pressure of the cooling water (Kcal / kg ℃) γ: specific weight of the cooling water (kg / m ³ ) This is the cooling water volume line that maximizes the efficiency gain value by comparing the amount of change in plant efficiency with changes in cooling water temperature and the amount of cooling water and the amount of efficiency improvement due to cooling water pump consumption power. By the way, the change in efficiency due to the change in cooling water temperature and the amount of cooling water comes from the change in condenser vacuum degree.
The relationship between the degree of vacuum change and the efficiency change is as shown in FIG.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, control consideration is not given to the fact that the economic operation line changes when the cleanliness of the condenser cooling pipe changes, and therefore optimal economic operation is achieved. There was a problem of not becoming.

That is, the economic operation line changes if the condenser vacuum degree changes as described above, but the condenser vacuum degree is calculated by the saturated pressure with respect to the steam temperature given by the equation (2), and In addition to heat load, cooling water inlet temperature, cooling water flow rate, if the cleanliness (φ ₂ ) of the cooling pipe changes, this consideration is not made in the prior art, and the economic operation line is condensate. It was created with a constant cleanliness design.

However Here t _s: condenser in steam temperature (℃) t _1: the cooling water inlet temperature (° C.) S: cooling area (m ²⁾ K: heat transmission coefficient ^{(Kcal / m 2 h ℃)} φ 1: cooling water Correction coefficient for inlet temperature φ ₂ : coefficient of cleanliness of cooling tube for dirt on cooling tube φ ₃ : correction coefficient for cooling tube material and wall thickness C: constant determined by cooling tube outer diameter V: cooling tube Average flow velocity in pipe (m / s) Q: G _W · C _P · γ: Same as the symbol in equation (1).

Cooling pipe cleanliness generally depends on operating conditions (sulfuric acid
(Injection of iron and chlorine, etc.), cleaning frequency of cooling pipes, elapsed time after cleaning, deterioration over time, etc., but as an example, FIG. 6 shows an example of the cleaning frequency and the change in cleanliness with elapsed time.

An object of the present invention is to provide a condensate cooling water flow rate control device that enables optimum economic operation even when the cleanliness of the condenser cooling pipe changes from the designed cleanliness.

[Means for solving problems]

The purpose of the above is to obtain the actual (current) cooling pipe cleanliness of the condenser,
If it differs from the design cleanliness, the cleanliness is used to simultaneously calculate the condenser vacuum and the cooling water flow rate that maximizes the plant efficiency gain, and the deviation between the actual (current) cooling water quantity and the calculated cooling water quantity This is achieved by correcting the flow rate command value in the prior art by a considerable amount.

Here, the present invention relates to an economic operation line obtained for the temperature signal of each condenser inlet cooling water in the relationship between the output signal of the generator and the condenser cooling water flow rate signal, and the condenser inlet cooling The flow rate command value signal is obtained from the relationship between the water temperature signal and the limiting line obtained based on the temperature signal of the condenser outlet cooling water, and the deviation between the flow rate command value signal and the condenser cooling water flow rate. In a condenser cooling water flow rate control device for controlling a cooling water flow rate to a condenser based on, a detector for detecting the degree of vacuum of the condenser, and a condenser vacuum obtained from the detector. Degree signal, the temperature signal of the condenser inlet cooling water, and the temperature signal of the condenser outlet cooling water, the degree of cleaning of the condenser is obtained, and the plant efficiency gain becomes maximum from the degree of cleaning. A calculator for determining the degree of vacuum and the amount of cooling water of the condenser is provided, and Plant efficiency gains are those based on said amount of cooling water of the condenser with the maximum flow rate command value signal is corrected to be optimum economic production value.

[Action]

The condenser vacuum degree and the amount of cooling water that maximize the plant efficiency gain due to the actual condenser cleanliness are calculated in (2),
Using the equations (3) and (4) and FIGS. 4 and 5, it is also possible to correct the flow rate command value in the prior art by the amount corresponding to the deviation between the actual cooling water amount and the calculated cooling water amount. It deserves to make the economic operation line of the prior art the optimum economic operation line.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

FIG. 7 shows an embodiment to which the present invention is applied.

The detectors shown in the figure correspond to the detectors shown in FIG.

In FIG. 7, 1 is a generator output detector, 2 is a cooling water inlet temperature detector, 3 is a cooling water outlet temperature detector, 4 is a cooling water flow rate detector, and 5, 6, 7, and 8 are initial stages, respectively. Flow rate command value generator, adder, controller Condenser vacuum degree detector, which is 9,10,11,12
Are the condenser vacuum level, the cooling water flow rate calculator, the corrected cooling water flow rate calculator, and the flow rate command value corrector, each of which is the center of the present invention.

First, using the generator output detector 1 and the cooling water inlet temperature detector 2, the initial flow rate command value generator 5 creates flow rate command values as in the conventional economic operation line, and the flow rates of 12 ΔT of the temperature obtained from the cooling water inlet temperature detector 2 and the temperature obtained from the cooling water outlet temperature detector 3 with the command value corrector
Performs initial control of the upper pump movable blade with limitation.

Next, by using the flow rate obtained from the cooling water flow rate detector 4 by the initial control, the temperatures of 2 and 3 described above, and the vacuum degree obtained from the condenser vacuum degree detector 8 of 8, the recovery of 9 is performed. Calculate the cleanliness with a waterware cleanliness calculator.

Since cleanliness is usually calculated as in equation (5), Where φ ₂ d: Designed cooling pipe cleanliness K: Modified thermal transmission coefficient (Kcal / m ² h ℃) obtained by converting the actual thermal transmission coefficient into the design state Kd: Designed thermal transmission coefficient (Kcal / m ² h ℃) The process data obtained with the detector is directly used for the calculation of the corrected heat transmission coefficient.

When the cleanliness is obtained in 9, the above (2), (3),
Using equation (4), the condenser vacuum and cooling water flow rate calculator that maximizes the efficiency gain of 10 calculates the cooling water flow rate that maximizes the gain.

The deviation between the flow rate and the actual (current) cooling water amount is calculated by 11 correction cooling water amount calculators, and is given to 12 flow rate finger cooling value correctors to correct the flow rate command value to the optimum economic operation value. .

At this time, the ΔT limitation is taken into consideration as in the prior art.

〔The invention's effect〕

According to the present invention, even if the cleanliness of the condenser cooling pipe changes significantly depending on the operating conditions, the movable blade opening of the condenser cooling water pump is set to the optimum position in terms of plant efficiency (optimal economic operating water amount). It has the effect of controlling the movable blade opening).

[Brief description of drawings]

Fig. 1 is a condenser cooling water system diagram, Fig. 2 is a conventional cooling water flow rate control device, Fig. 3 is a movable blade cooling system operation diagram, and Fig. 4 is a movable blade pump economic operation water amount. Fig. 5 is an examination diagram, Fig. 5 is a condenser vacuum degree thermal efficiency correction curve, Fig. 6 is a relationship diagram of cleaning frequency and cleanliness, and Fig. 7 is a cooling water flow rate control device according to the present invention.

Claims (1)

[Claims] 1. An economic operation line determined for a temperature signal of each condenser inlet cooling water in the relationship between an output signal of a generator and a condenser cooling water flow rate signal, and the condenser inlet cooling water. The flow rate command value signal is obtained from the relationship between the temperature signal and the limit line obtained based on the temperature signal of the condenser outlet cooling water, and the deviation between the flow rate command value signal and the condenser cooling water flow rate signal is determined. A condenser cooling water flow rate control device for controlling the flow rate of cooling water to the condenser based on a detector for detecting the degree of vacuum of the condenser, and the degree of vacuum of the condenser obtained from the detector. The degree of cleaning of the condenser is obtained based on a signal, a temperature signal of the condenser inlet cooling water, and a temperature signal of the condenser outlet cooling water, and the plant efficiency gain becomes maximum from the degree of cleaning. A calculator for determining the degree of vacuum of the condenser and the amount of cooling water is provided. Plant efficiency gain condenser cooling water flow rate control device, characterized in that the flow rate command value signal is corrected such that the optimum economic operation value based on the amount of cooling water of the condenser becomes maximum.